Iran claimed to have taken surveillance footage of a US aircraft carrier near
the Strait of Hormuz as both countries raised the stakes in their standoff
over the key oil route.

The commander of Iran's navy said the reconnaissance mission was proof that his fleet had "control over the moves by foreign forces" but it was unclear what intelligence could be derived from the grainy video, which was played triumphantly on state television.

Admiral Habibollah Sayyari's statement came as Iranian ships, helicopters and submarines continued a 10-day war game exercise designed to give credibility to the country's threat to close the Strait and choke off the world's oil supplies if the West moves ahead with sanctions.

The drill is underway in international waters near the Strait and only a few hundred miles from America's Bahrain-based Fifth Fleet. The US Navy has vowed to prevent any closure of the channel, through which 15 million barrels of oil pass every day.

A Navy spokeswoman would not comment on the footage but confirmed that the USS John C Stennis, one of the fleet's largest carriers, was on a "routine transit" through the Strait to provide support to Nato forces in Afghanistan.

Despite the Fifth Fleet's advantage in firepower, a senior Revolutionary Guard commander vowed yesterday that "Any threat will be responded [to] by threat."

"We will not relinquish our strategic moves if Iran's vital interests are undermined by any means," General Hossein Salami told Press TV.

This afternoon, the US also announced it was selling more than 80 F-15 strike aircraft to Saudi Arabia, an American ally and Iran's main rival for military dominance in the Middle East. Without specifically naming Iran, the State Department said the sale was intended as "a strong message to countries in the region that the United States is committed to stability in the Gulf and broader Middle East."

Barry Pavel, Director of the Brent Scowcroft Centre on International Security at the Atlantic Council, said that Iran's navy was potentially capable of closing the Strait but would be unlikely to do so because of the country's dependence on revenues from oil exports. "It would have to be a very extreme situation for Iran to basically shut down its own economy," he said.

The Iranian threat to close the narrow shipping lane was made after the EU, backed by the US, announced it was tightening sanctions on Iran for pressing ahead with its nuclear programme. Europe buys around 20 per cent of all Iranian oil exports and a full embargo would cause serious damage to Iran's economy.